Strength, porosity and permeability of sintered bodies made from glass microspheres

¹ Physics Department, University of Aveiro, 3810-193 Aveiro, Portugal
² Glass and Ceramic Engineering Department, CICECO, University de Aveiro, 3810-193 Aveiro, Portugal

Corresponding author: skm@fis.ua.pt

Received: 18 March 2004
Revised: 30 September 2004
Accepted: 22 October 2004
Published online: 28 January 2005

Abstract

Solid bodies obtained by sintering glass microspheres through the first stage of sintering have the useful characteristics of large porosity combined with adequate mechanical strength. Additionally, if the microspheres all have the same diameter, the pore morphology is well defined in terms of shape and has a narrow distribution in size parameters. The two major areas of application of the porous bodies are: A. light weight but mechanically strong objects, and B. filtration of liquids. The fracture strength and the specific liquid permeability of these bodies are expressed as empirical functions of volume porosity (ratio of empty volume to the total volume). Here, we describe the results of our systematic study of the geometrical properties like density, linear contraction and global porosity parameter φ, and the flow parameter, the permeability coefficient as a function of the sintering conditions. Our analysis shows that the existing relations, property versus φ, that claim to describe the behaviour are not adequate for our simple system. We think that the contact area between the adjoining spheres is a better parameter to consistently describe a larger set of the properties. Since, for the initial stage sintering of single diameter spheres, the contact area and the pore size can be expressed as a function of linear contraction, latter is a better universal parameter in terms of which the regular features of the property variations can be expressed.